Field
Embodiments described herein generally relate to magnetrons used in physical vapor deposition process. In particular, embodiments described herein relate to an encapsulated magnetron.
Description of the Related Art
Physical vapor deposition (PVD), alternatively called sputtering, is a method of depositing layers of metals and related materials in the fabrication of integrated circuits. PVD was developed to deposit planar metal layers used for interconnects. Commercial PVD typically utilizes a plasma of a sputter working gas, such as argon, to bombard the negatively biased target with argon ions to sputter atoms of the target material, which thereafter coat a substrate with a layer of the target material. Plasma discharges are typically formed in the process chamber by DC or RF voltages, microwaves, planar magnetrons, or a combination of techniques.
A planar magnetron system typically uses a rotating magnetron disposed above a target and either a DC bias between the target and the substrate and/or an RF source coupled into the space between the target and substrate to form the plasma. The magnetron is a magnet assembly that provides magnetic field lines near the sputtering surface of the target. A negative bias voltage between the target and the plasma region accelerates the ions toward the target to dislodge the target material therefrom. The magnetic field from the magnetron confines the free electrons, including secondary electrons displaced from the target material, near the target to maximize the ionizing collisions by the free electrons with the sputtered material. The magnetron typically includes one or more magnets, which rotate around the backside, i.e., non-sputtered surface, of the target to evenly spread the magnetic field around the surface of the target to result in more uniform sputtering of the target material.
The plasma used in the PVD process may heat up the target. If the magnetron and/or the target are heated above a designated process temperature, then the high temperature may after the performance of the process by changing the sputtering rate or sputtering uniformity on the target and lessening the useful lives of the magnetron and the target. Conventionally, targets are cooled by having the backside exposed to a cooling fluid, such as deionized water, which is housed in the magnetron cavity. The magnetron is disposed in the magnetron cavity and the magnets and support structures may be corroded by the heat and the cooling. In addition, handling the magnetrons can be problematic with the open structures and can lead to hardware handling problems as dropped hardware can become lodged in the internal structure of the magnets and is difficult to remove.
Therefore, an improved magnetron is needed.